When process equipment is engulfed in a fire, the protection system should extinguish the fire and simultaneously cool the equipment. Therefore, the behaviour of equipment engulfed in a fire, as well as its eventual influence on the fire, should be known. In this article, experimental data from pool fires of hexane (4 m(2)) and kerosene (12 m(2)) are discussed. The evolution of the fire up to its full engulfment is studied, as is the evolution of temperatures at different points of a tank engulfed in it. The heat release rates under the different operating conditions are studied. A method is developed to calculate the maximum combustion rate, both for the developing stage and for the fully developed fire. The hindering effect of the tank on the fire is discussed and quantified in terms of ＇efficiency of hindered combustion＇.